Chesapeake Energy has stemmed the flow of leaking drilling fluids from a natural gas well that suffered a blow-out late on Tuesday in Pennsylvania and prompted the company to suspend a controversial gas production technique in the state.

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Chesapeake, one of Pennsylvania's biggest shale gas producers, used a mix of plastic, ground-up tires and heavy mud to plug the well -- an operation that echoes BP's "top kill" effort to seal its ruptured Gulf of Mexico oil well last year.

"Late Thursday afternoon, efforts to seal the leak and regain control of well pressure were successful," Chesapeake said in a statement on Thursday evening.

The company said it still did not know the cause of the blowout nearly two days after it occurred. It was planning to start an investigation into the accident, the statement said.

The blowout in northeastern Pennsylvania, which spilled toxic fluid into a local waterway, has stoked an already fierce debate in the United States over hydraulic fracturing, or fracking -- a process to release gas trapped in shale formations by blasting a mix of water, sand and chemicals into the rock.

Proponents say extracting shale gas through fracking will slash U.S. reliance on foreign oil and cut carbon emissions. President Barack Obama has made natural gas the cornerstone of his energy policy, in part thanks to the huge reserves unlocked by the use of fracking. Shale gas now accounts for 23 percent of U.S. natural gas production, rising from a negligible amount in 2004.

But environmentalists and residents complain that fracking can pollute water supplies, raising calls for increased regulation on natural gas production.